Stair form



April 7, 1931. I o s 1,799,405

' STAIR FORM Filed Feb. 4, 1930 NATHANIEL 5015 Patented Apr. 7, 1931 UNITED STATES NATHANIEL 1301s, or sAN FRANCISCO, CALIFORNIA STAIR FORM Application filed February 4, 1930. Serial No. 425,789.

My invention relates to improvements in sheet metal stair forms wherein the tread portion of each stair is provided with a longitudinal groove formed upon the under side thereof to engage the upper edge of a riser, said groove operating to form a seat holding said tread and riser in operative relation and concealing the joint between adjacent forms.

The primary object of my invention is to provide an improved stair form for stair construction.

Another object is to provide an improved stair form wherein the upper edge of each riser is engaged in a groove formed in the under side of the thread of the next higher stair form to hold the forms in fixed relation to each other. v

A further object is to provide an improved stair construction wherein stair forms of simplified and improved construction are effectually positioned relative to each other and secured between stringers to form a flight of stairs, each tread being held in seated relation upon the upper edge of the next lower riser.

A still further object is to provide an improved device of the character describedof simple and economical construction WlllCh can be manufactured and installed at a relatively low cost.

I accomplish these and other objects by means of the improved device disclosed in the drawings forming a part of the present application wherein like characters of reference are used to designate similar parts throughout the specification and drawings, and in which- Fig. 1 is a broken sectional view of my improved stair form and stair construction, various arrangements of the means for securing the forms to the stringers being illusv trated in connection with the several stair 5 forms shown;

Fig. 2 is a section taken upon the line 2-2 of Fig. 1 in the direction indicated; and Fig. 3 is a broken transverse section of a stair form, drawn upon a larger scale; and illustrating different positions in which the tie-rod may be secured between a pair of stringers.

Referring to the drawings, the numerals 1 and 2 are used to designate the tread and riser portions of a stair form, said tread and i riser preferably being formed integrally from suitable sheet metal. A groove 3 is formed in the under side of the tread 1 of each form, said groove being formed by indenting the sheet material longitudinally across the tread from end to end and form.- ing an upwardly extending rib 4. The groove 3 and rib 4 are spaced rearwardly from the front edge of the tread an amount equal to the amount the tread normally overhangs the riser in a flight of stairs.

The front edge of the tread 1 is shaped to form an upwardly disposed nosing 6 having a rearwardly disposed flange 7 substantially parallel to the tread 1. The juncture of the tread 1 and riser 2 of each form is preferably offset to form a' recess 8, the recess 8 being substantially opposite the recess formed by the nosing 6 and flange 7 across the front of the tread.

The forms are mounted between a pair of stringers 11. The forms are secured to the stringers at the back of each form, preferably y means of a tie-rod 12 extending longitudinally through the recess 8 and having its ends extending through apertures formed in the stringer.

The front edge of each tread is held in operative position seated upon the top of the next lower riser and with the upper edge of said riser received within the groove 3 by means of a tie-rod 15. The ends of the tierod 15 extend through apertures formed in the stringers 11, and the rod is applied in 0 contact with the upper surface of the tread 1 to hold said tread rigidly against the top of the riser. The rod 15 is preferably placed immediately back of the rib 4 so that the rib 4 operates to prevent the tread 1 from being 95 moved rearwardly. If desired, the rod may be placed immediately in back of the nosing 6, thereby preventing rearward movement of the tread in the same manner. Forward movement of the tread is prevented by the rod 12 and also by the adjacent riser en gaging the groove 3.

n o ration, the stair forms are placed successively between the stringers 11, the upper edge of each riser 2 being received within the groove 3 of the next higher tread. The tie-rods are inserted to hold the forms in their operative position, said rods being provided with offset portions 17 engaging one stringer. Nuts 18, applied upon the threaded ends 19 of the tie-rods, are then tightened to clamp the stringers ll rigidly against the ends of the stair forms. The rearward por tions of the stair forms are rigidly supported by the tie-rods 12. The front end of each tread is supported by the next lower riser, and the tle-rod 15 effectually holds the grooved portion of the tread seated upon the risers.

When the forms have been thus installed, cement or other suitable material is applied to fill the forms to the level of the flange 7, as indicated in dotted lines in the drawings. The tie-rods 12 and 15 are embedded in the cement, thereb effectually reinforcing the cement and binding the entire construction into a rigid structure. The groove 3 conceals the top edge of the riser so that the joint between the riser and the next higher tread cannot be seen.

Various modifications may be made in the specific details of construction without de-.

parting from the spirit of my invention. I therefore desire to avail myself of all modifications which may fall within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is i 1. A stair form comprising a tread and riser, said tread having a longitudinally disposed groove formed upon the under side thereof to engage the upper edge of an adjacent riser; and means for securing the groove of the tread seated upon the riser.

2. A stair form comprising a tread and riser, said tread having a longitudinally disposed groove formed upon the under side' thereof to engage the upper edge of an adjacent riser; and a tie-rod extending longitudinally across the tread and in contact therewith to hold said groove in engagement with said riser.

3. A sheet metal stair form comprising a tread and riser, said tread having a longitudinally disposed groove formed upon the under side thereof to seat upon the upper edge of an adjacent riser; and a tie rod extending longitudinally across the tread to hold said tread seated upon the riser and engaging an upwardly extending portion opposite the groove of the tread to prevent shifting of the form.

4. A stair form comprising a tread and riser, said'tread having a longitudinally disposed groove formed upon the under side thereof to seat upon the upper edge of an adjacent riser; means engaging the form adjacent the rearward edge of the tread to secure said form to a pair of stringers adjacent the ends of the form; and a tie-rod extendformed longitudinally from end to end upon the under side to receive the upper edge of the next lower riser; means engaging each form adjacentthe juncture of the tread and riser to secure said forms to the stringers; and tie-rods extending between the stringers immediately above the groove in the tread of each form and holding said tread seated upon the top of the adjacent riser.

6. The combination with a pair of stringers, of a plurality of stair forms mounted between the stringers, each form comprising a tread and riser, each tread having a groove formed longitudinally from end to end upon the under side to receive the upper edge of the next lower riser; means engaging each form adjacent the juncture of the tread and riser to secure said forms to the stringers; and tie-rods extending across the tops of each tread and extending through the stringers to hold said tread seated upon the top of the adjacent riser. said rods being engaged by an upwardly extending portion opposite the groove of each tread to prevent lateral shifting of the form relative to the stringers and the adjacent forms.

In witness whereof, I hereunto set my signature.

NATHANIEL B015. 

